Stabilization of furnace oil by hydrotreating to remove sulfur and gum



June 1958 w. P. BURTON ETAL 2,840,512

STABILIZATION OF FURNACE OIL BY HYDROTREATING TO REMOVE SULFUR AND cumFiled Sept. 29, 1955 3 INVENTORS w WILLIAM P. BURTON CHARLES E.SLYNGSTADATTORNEYS United States Pfltfiflt O STABILIZATION OF FURNACEOIL BYHYDRO- TREATING TO REMOVE SULFUR AND GUM William P. Burton, LittleSilver, and Charles E. Slyngstad, Rutherford, N. J., assignors to The M.W. Kellogg Company, Jersey City, N. J., a corporation of DelawareApplication. September 29, 1955, Serial No. 537,414

4 Claims. (Cl. 196-24) This invention relates to a method of stabilizinga furnace oil'without effecting a change in color.

Furnace oils are used extensively in home burners and commercialinstallations for heating, etc. At present, there is found in furnaceoils gum-forming compounds or constituents which will, upon standing,produce gum-like materials. These gum-like materials are not desired,because in the type of equipment used for burning furnace oils, thegum-like materials will clog the equipment causing operatingdifliculties. At present, it is not clearly understood what kind ofcompounds produce the undesired gum-like materials. Further, furnaceoils contain color bodies or compounds which impart to the oil a colorother than a colorless appearance. These color bodies do not causeoperating difficulties in the equipment used for the burning of furnaceoils, therefore, for the purpose of this invention, it is not intendedto effect any change in the color of the oil. In addition to the colorbodies and the gum-forming compounds, the furnace oils do contain sulfurcompounds. The combustion of sulfur compounds in the furnace oil mayproduce corrosion of the equipment used for such a purpose as well as toproduce an undesired smell or contamination of the surroundingatmosphere. It is apparent, therefore, that there exists a need for aprocess whereby furnace oil can be stabilized, with or withoutsimultaneous removal of sulfur and without a change in color.

An object of this invention is to provide a process for thestabilization of furnace oils without a, change in color.

Another object of this invention is to provide a method for thedesulfurization and stabilization of furnace oils without changing thecolor. I

Other objects and advantages of this invention will become apparent fromthe following description and explanation thereof.

By means of the present invention, a furnace oil is stabilized without achange in color by the process which comprises contacting the furnaceoil containing gumforming constituents with a cobalt molybdate. catalystunder suitable reaction conditions including a temperature not greaterthan 700 F. and a weight space velocity of at least about 5.

The furnace oil to bev processed by means of the present inventioncontains gum-forming constituents. The determination of the gum-formingtendency of the furnace oil or its stability is made by a simple testinwhich the oil is subjected to a temperature of 210 F. for a period of 40hours. If the oil does not change more than /2 NPA in color and not morethan 5 milligrams of gum is produced per 600 grams of oil sample, it isconsidered stable. This test is used for the purpose of determining thestability in the present specification and the appended claims. Whilethe gum-forming compounds or constituents in the furnace oil are notknown at present, nevertheless the stability test is sufficient for thepurpose of determining the nature of a particular furnace oil. Inaddition to. stability, furnace 'oils usually contain color. Here again,at present, the color bodies or compounds imice parting color to thefurnace oil are not clearly understood, although it is speculated thatnitrogen compounds usually produce color, in hydrocarbon oils. For thepurpose of this invention, the furnace oil can contain an NPA colorranging from about 1 to about 6 or on a Saybolt scale, the color of thefurnace oil can range from about I6 to about +30. In addition tocontaining color and gumforming compounds, the furnace oil may alsocontain sulfur compounds. The sulfur concentration of a furnace oil canvary widely such as, for example, about 0.1 to

about 4% by weight of sulfur. The sulfur content of the oil will bereduced under the conditions employed for the purpose of effectingstabilization. The furnace oil employed for the purpose of thisinvention will have an initial boiling point of about 300 to about 420F. and an end point of about 500 to about 850 F., more usually, thefurnace oil will have an initial boiling point of about 325 to about 350F. and an end point of about 550 to about 650 F. The furnace oil to betreated can be a mixture of virgin or straight run stock and what isusually refered to as light cycle oil, as well as heavy cycle oils.

The furnace oil is treated by means of a cobalt molybdate catalyst.Forthe purpose of this specification and the appended claims, cobaltmolybdate is intended to include a mixture of cobalt oxide andmolybdenum oxide as well as the compound cobalt molybdate. It isbelieved that under the conditions employed for the purpose of treatmentin accordance with this invention, it is not important whether a mixtureof the oxides is used or whether cobalt molybdate is the catalyst at thestart of the operation. Accordingly, the catalyst of this inventioncontains about 0.5 to about 10% of cobalt oxide, based on the totalweight of the catalyst, and it contains about 5 to about 25% ofmolybdenum oxide, e. g., molybdenum trioxide, based on the total weightof the catalyst. The cobalt molybdate is supported on a suitable carriermaterial, such as for example, alumina, silica-alumina, halogenatedalumina, activated charcoal, kieselguhr, pumice, zinc aluminate spinel,etc. When silica is employed in combination with alumina, it constitutesabout 0.5' to about 5%, based on the total weight of the catalyst.Chemically combined halogen such as, for example, chlorine or fluorine,can be used in the catalyst in the amount of about 0.1 to about 8%,based on the total weight of the catalyst.

'The furnace oil is treated with cobalt molybdate catalyst undercarefully selected conditions. In this respect, it is essential to thepresent invention that the temperature of treatment is not higher thanabout 700 F. and the weight space velocity is at least 5. In thisrespect, should either thetemperature or the weight space velocity falloutside of the range given above, it is noted that there is a colorchange, and hence, such an operation falls outside the scope of thisinvention. In general, the temperature of treatment can vary from about550 F. butnot greater than about 700 F. The weight space velocity,measured as the pounds of oil per hour charged to the reaction zoneperpound of catalyst present therein, is at least. about 5 and. it can beas high as 20. It was found that the pressure of operation can be as lowas about p. s. i. g. and it can be as high as 1500 p. s. i. g., moreusually about 300 to about 1000 p. s. i. g. The reaction.

a hydrogen rate of up to about 2000 S. C. F. B. sufiices for the purposeof this invention. Consequently, it can bev seen that the presentinvention can be operated within rather narrow ranges of conditions, forexample, a high 3' hydrogen rate of about 300 weight space velocity ofabout 5 to about 15 and a reaction pressure of about 300 to" about 600p. s. i. g. Under the conditions of operation, at least part of thesulfur content in the furnace oil is removed, the oil is stabilized andthe color remains unchanged.

In order to provide a better understanding of this invention, referencewill be had to the accompanying drawing which contains a schematicdiagram of a test unit which was employed for. the purpose ofevaluatingthis invention.

1 Inthe drawing, oil feed is supplied by means of line 5 at the desiredflow rate and it is combined with hydrogen being supplied from line 7,and thence, the combined steam flows throughline 8 before enteringpreheater 10. In the preheater, the temperature'is raised to the desiredtemperature, for example, about, 600 to about 700 F., and thereafter, itflows through line 12 before it enters the top of reactor 14. Reactor 14is 43 inches in length andll inches in diameter, and it contains about800 grams of catalyst. The catalyst is in the-form of 35 inch pellets.Under the conditions prevailing in the reactor, theffurnace oil isstabilized with removal of sulfur and without change in color. Thevaporous reaction product is discharged from the bottom of the reactorby means of line 15,;and hence, it enters a water cooler 17 wherein thetemperature is reduced to about 80 F. The cooled reaction productcontains condensed normally liquid product material, or material whichis present as a liquid under reaction pressure and the temperature towhich the material was cooled; The cooled reaction product flows fromcooler 17 -by means of line 20.

. A preliminary separation of normally gaseous product materialfromliquid product eflected ,in primary'receiver l9, consequently, thenormally gaseous product material flows overhead therefrom by means ofline 22;

Whereas the liquid product is discharged from the bottom by means ofline 23. Any liquid product which is entrained in the normally gaseousproduct is separated in the secondary receiver 25 and it isdischarged'from the bottom thereof by means of valved line 27. Thegaseous product is discharged overhead from the secondary. receiver. 25by means of line 28. The liquid product in lines 23 and 27 flow intoline 30'which contains. a pressure) reducing valve 31. By means of valve31, the pressure; ,is reduced to atmospheric level and the total productpasses into a low pressure receiver 32. Any gaseous product which isreleased from the liquid product in receiver 32 is discharged therefromby means of line 34 and it is measured by means of meter35 before beingvented from the system by, means of line 36. Liquid product is dis- 5 ina closed position. Hydrogen can be purged from the o 1 system via line46. Fresh hydrogen is supplied from a valved line 50, and it flows toline 51 before being measured by means of, meter 53. The measuredhydrogen flows from'meter 53 to line 55 where, in the case of therecycle gas: operation, it combines with recycle gas flowing throughline 42 and the combined stream flows through line 57. The totalhydrogen stream is measured by meansof meter 59, and thence, it flowsintoline 7 beforecombining with feed which is flowing to the preto about900 s. c. F. 15., a o

' 4 a mixture with the air in case a diluted air stream is desired forthe regeneration.

The feed stocks evaluated for the purpose of this invention are given inTable I below.

Table I Feed A B 0 D API Gravity 24. 0 23.8 29.9 33. 4 ASTMDistillation, F.:

IBP 386 433 466 326 472 481 504 408 639 536 536 518 605 608 600 586 E. P649 644 642 639 Sulfur, Wt. percent 1. 02 2.13 0. 21 0. 18 Color, NPA 23% 2 1% heater l0. For the purposeof regeneration, air can be suppliedfrom a valved line 61 and valved line 50-can be employed for the purposeof supplying nitrogen for ad The catalyst employed for this evaluationconsisted of cobalt molybdate supported on alumina. The catalystcontained 4.1% by weight of cobalt oxide, 12.0% by weight of molybdenumtrioxide and the remainder was alumina. e

The data reported in Table 'II below serves to illustrate thecriticalfeature of temperature when it is desired to stabilize furnace oilswithout changing color.

I 807 hydrogen.

a hydrogen.

\1 Stable oil is defined herein as changing not more than $6 NPA colorand producing no more than 5 mg. gum/600 gm. 011 during the stabilitytest oi 40 hours in a 210 F. oven.

It is apparent from the data given above in Table II that as long as thetemperature was above 700 F., notwithstanding that all other conditionsfall within the range tobe used for the treatment of furnace oil inaccordance with this invention, the oil product was stabilized with achange in color.

Additional experiments were performed and reported in Table m below. a

Table 111 Run N0 1 2 a 4 Feed A A A A Pressure, p. s. l. g 400 400 400400 Space Vel., W.,/hr./W... l 5 10 10 Temperature, F 700 700 700 780 H;rate, S. C. F. B 500 520 520 480 Results Feed Products Sulfur, we.percent"; 1 02 0,05 0. 24 0.38 o. 21 Color, NPA 2' 2 2 8% Stability N 0Yes Yes Yes Yes a It is apparent from the data contained in Table IIIabove thatwhere the temperature was 700 F. and the weight space velocitywas at least 5, the furnace oil was stabilized without a change incolor. However, where the temperatureof treatment was 700" F. and theweight space velocity was below 5, the oil was stabilized with a changein color. Further, when etfecting the treatment above 700 F. with aweight space velocity of 10, it is noted that the oil was stabilizedwith a change in color.

Further evaluation of the present invention was made and the results arereported in Table IV below.

Table IV Run No 1 2 Fee A A Pressure, p. s. i. g 400 400 Space Vel., Wr./Wc 1.0 1. 0 Temperature, F 700 700 H: rate, S. C. F. B 500 2,000

Results Feed Products Sulfur, Wt. Percent 1. 02 0. 0. 05 Color, NHL... 24 3 Stabi1ity N 0 Yes Yes The data in Table IV above indicate that eventhough a higher rate of hydrogen is employed for the treatment just solong as the weight space velocity falls below 5, the furnace oil isstabilized with a change in color.

An additional experiment was performed and reported in Table V below.

Table V Run No 1 Feed 0 Pressure, p. s. i. e 600 Space Vel., W.,/hr./W.,5 Temperature, F 700 H; rate, S. O. F. B 800 Results Feed ProductSulfur, Wt. Percent 0. 2 0. 03 Color, NPA 2 2 Stability No Yes It isnoted from the run made and reported in Table V above that the criticalaspects of temperature and weight space velocity are not disturbed byusing a higher'pressure of treatment.

Another experiment at low pressure was performed and reported in TableVI below.

is possible to operate at as low as p. s. i. g. with only a very smallchange in color in the oil treated to provide a stable oil ofsubstantially lower sulfur content.

Having thus provided a written description of this invention along withspecific examples thereof, it should be understood that no unduerestrictions or limitations are to be imposed by reason thereof, butthat the scope of the present invention is defined by the appendedclaims. We claim:

1. A process for stabilizing a furnace oil containing gum formingconstituents without changing the color thereof which comprisescontacting the furnace oil with a cobalt molybdate catalyst undersuitable reaction con ditions including a temperature not greater thanabout 700? F. and a weight space velocity of at least about 5.

2. A process for stabilizing a furnace oil containing gurn formingconstituents without changing the color thereof which comprisescontacting the furnace oil with a cobalt molybdate catalyst undersuitable conditions including a temperature not greater than about 700F., a weight space velocity of at least about 5, a hydrogen rate in theamount of at least about 300 S. C. F. B. and a pressure of at leastabout 150 p. s. i. g.

3. A process for desulfurizing and stabilizing a furnace oil containinggum forming constituents and sulfur compounds without changing the colorthereof which comprises contacting the furnace oil with a cobaltmolybdate catalyst under suitable desulfurization conditions including atemperature not greater than about 700 F., a weight space velocity of atleast about 5, a pressure of about 150 to about 1500 p. s. i. g. and inthe presence of added hydrogen in the amount of about 300 to about 20008.0. F. B.

4. A process for desulfurizing and stabilizing a furnace oil containinggum forming constituents and sulfur compounds without changing the colorthereof which comprises contacting the furnace oil with a cobaltmolybdate catalyst under suitable conditions including a temperature ofat least about 550 F. and not higher than about 700 F., a weight spacevelocity of about 5 to about 20, a pressure of about 150 to about 1500p. s. i. g. and in the presence of added hydrogen in the amount of about300 to about 2000 S. C. F. B.

References Cited in the file of this patent UNITED STATES PATENTS2,587,987 Franklin Mar. 4, 1952 2,608,521 Hoog' Aug. 26, 1952 2,694,671Baumgarten et a1. Nov. 16 1954 2,717,857 Bronson et al. Sept. 13, 1955OTHER REFERENCES Zohnstecher et al.: Oil and Gas Journal, vol. 53,December 20,1954, pages 78 to 81. r

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,2,840,512 June 24, 1958 William P, Burton et al It is hereby certifiedthat error appears in the printed specification of the above numberedpatent requiring correction and that the said Letters Patent should readas corrected below.

Column 3 line 15, for "steam" read stream line 26, for

"hence" read thence Signed and sealed this 19th day of August 1958,

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner ofPatents

4. A PROCESS FOR DESULFURIZING AND STABILIZING A FURNANCE OIL CONTAININGGUM FORMING CONSTITUENTS AND SULFUR COMPOUNDS WITHOUT CHANGING THE COLORTHEREOF WHICH COMPRISES CONTACTING THE FURNACE OIL WITH A COBALTMOLYBDATE CATALYST UNDER SUITABLE CONDITIONS INCLUDING A TEMPERATURE OFAT LEAST ABOUT 550*F. AND NOT HIGHER THAN ABOUT 700*F., A WEIGHT SPACEVELOCITY OF ABOUT 5 TO ABOUT 20, A PRESSURE OF ABOUT 150 TO ABOUT 1500P. S. I. G. AND IN THE PRESENCE OF ADDED HYDROGEN IN THE AMOUNT OF ABOUT300 TO ABOUT 2000 S. C. F. B.